The present invention relates to a power transmission control device, a power reception control device, a non-contact power transmission system, a power transmission device, a power reception device, an electronic instrument, and the like.
In recent years, non-contact power transmission (contactless power transmission) which utilizes electromagnetic induction to enable power transmission without metal-to-metal contact has attracted attention. As application examples of non-contact power transmission, charging a portable telephone, a household appliance (e.g., telephone handset), and the like has been proposed. JP-A-2006-60909 discloses a non-contact power transmission device using a primary coil and a secondary coil, for example.
In a related-art non-contact power transmission system, a power reception device corresponding to given load conditions is provided. A power transmission device which can transmit power to the power reception device under optimum conditions is necessary. The power transmission device are adjusted in terms of the drive frequency and the impedance of a power transmission section so that best power transmission characteristics are obtained when combined with the power reception device.
A power transmission device or a power reception device of which the power transmission or reception characteristics can be adjusted has also been known.
If the characteristics of a power transmission device and a power reception device are changed when the load of the power reception device is changed, the development period increases when designing different types of non-contact power transmission devices corresponding to the load. In JP-A-10-12467, a power regulation section is provided in a power reception device so that the characteristics of the power reception device can be adjusted to reduce the development period.
In JP-A-2005-210801, a plurality of small power supply coils are provided in a power transmission device. The number of small power supply coils used is adaptively changed corresponding to a change in load so that it is possible to deal with the load which changes in a wide range.
The non-contact power transmission system is expected to be widely used in various fields. In order to deal with such a demand, a power transmission device which can flexibly deal with various power-reception-device-side instruments is necessary.
For example, when utilizing the non-contact power transmission system for charging a secondary battery (load), an instrument provided with the secondary battery may be a portable terminal such as a portable telephone terminal, a PDA terminal, or a portable computer terminal. The non-contact power transmission system may also be used to charge a secondary battery provided in a digital camera, a wristwatch, or the like.
In a related-art non-contact power transmission system, it is impossible to deal with various instruments using a single power transmission device.
In a related-art non-contact power transmission system, when dealing with completely different power-reception-device-side instruments using a single power transmission device, for example, since the rated power of the power-reception-device-side instrument is unknown, optimum transmission power cannot be specified. Therefore, the power transmission device may transmit excessive power to the power reception device.
Moreover, the adjustment range of the power transmission characteristics of a related-art power transmission device is limited. This makes it difficult to deal with a wide variety of instruments as described above.